Method and apparatus for electrodepositing chromium



K. w. SCHWARTZ 1.720.354

HOD m APPARATUS POI WODIIOSI'HIG mu! July 9, 1929.

H.106 A ril 30. 1927 ldatented duly h,

lf dt WEVIE W. EBCH'WIMWIWZ, Elli" NEW roan, Ill. ill, assranon- TUGHHUIEIUQEE fjfiltll llllihdltlhl' Elli dltlihlhblfilt, A. oonroaarronor DELAWARE.

v MEUPHUJD .hllll) .rhIlPPJll-M'llli'lt FUR. ELEGTRUJDEPUdITING'UHRQMKUMT.

application filed hprll so,

This invention relates to methods and apparatus for electrodepositingmetals, such as chromium, on the inside of hollow articles,

connected as tathode, such as ipes, tubes, a vessels and the like, andprovides improvements therein. a

The present invention provides an improved method and apparatus forelectrodepositing metals, such as chromium, upon to the inside of hollowarticles, particularly where there is disengaged in the process ofelectrodeposition CODSlClGI'ablQ quantities of gas, as for examplehydrogen, and particularly where large surfaces are to be coated l andthe currentwill be inordinately large-in attempting to coat the entiresurface simultaneously.

The invention furthermore provides a method and apparatus particularlysuitable 80 for electrodepositing metal on the inside of hollow"articles in situ, articularly where-such articles have a consi erablevertical height. The invention also provides an'apparatus articularlyadapted to beingset up on the inside of hollow articles where theingress to such articles is through an opening of re stricted size. 1

An embodiment of the invention is illus trated inthe accompanyingdrawing. The an invention is illustrated as applied to theelectrodeposition of chromium on the inside of a large hollow reactionchamber such as is used in the processof craking oil.

In said drawings Figure 1 is a vertical sectional view through thereaction chamber, showing the electrode positing apparatus set uptherein. F ll ig. 2 is a cross-section on the line ill-ll, 3 is across-section on the line ll-ll-lll, 1g. 1.

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Numeral 10 designates the hollow article which is to he coated on itsinner surface with v a coating of metal. 'lhe vessel illustrated is alarge steel vessel such as is usedas a reaction chamber in an oilcraclring installation, and

on which an electrodeposit of chromium is to he produced on its innersurface. "lhese re-' action chambers are nsuallyejuite large, typt inn.renal in. tantra cal dimensions being to 40 feet in'hcight so and 10feet in diameter. 'lhese reaction chambers are usually provided withrestricted openings l2, 13 of a few feet in diameter at top and bottom.Many of these reaction chamhers are set up in installations, and it 'isdesirable to be able to electrodeposit the coating metal with the vessel10 in situ.

The preferred coating metal is chromium. Any suitable solution forelectrodepositing the chromium may be used. l prefenhovv till ever, oneof the known chromic acid solutions, such for example as disclosed inthe Grube Patent, hlo ldllfifilfi, granted June 10, 1924, or in the FinkPatent, No. 1,581,188, granted April 20, 1926.

ln electrodepositing chromium from chromic acid haths, there-is arelatively large disengagement of hydrogen which is released from thecathode sin-fact: as a gas, and the current densities used arerelatively large.

To attempt to electrodeposit chromium simultaneously over the entireinner surface of 'a vessel having the given dimensions of the vessel 10would, under ordinary conditions, require the use of about 100,000amperes. 7% Generators of this size would be inordinately large, and inany event it would in most cases be preferable to use generators of lessampere ratmg.

Furthermore, if it were attempted to electrodeposit chromium on theentire surface at once, the disengagement of the hydrogen would be sogreat as, under ordinary conditions, to interfere with the depositionbeing successfully effected over the entire surface.

According to the present invention, deposition is efi'ected on a part ofthe inner surface of the article 10 at a time, and this electrodepositis progressively extended over or around the entire surface. The portionof W the inner surface on which the electrodeposition starts isconveniently. a strip or strips. running lengthwise of the vessel. Thisstri extends over portions of the surface vvhic are angularly displacedwith relation to one another, the arrangement of such angularlydisplaced portions with relation to one another heing such that thehydrogen or other gas released at one portion of the cathode surfacereceiving deposited metal will not interfere with the deposition goingon on the adjacent portions of said strip.

The deposit in the manner just described is conveniently effected bymeans of an anode structure 20. The portion or portions of the anodestructure which directs the depositing current onto the strip of cathodesurface undergoing plating at any one time is designated by the numeral22. The anode part 22 is arranged lengthwise of the strip of the cathodesurface which is to be plated, and the anode part 22 is also arranged insuch manner that portions thereof, as the portions 25, 26, 27, 28, 29,30, 31, 32, 33, 34, 35, 36, 37 are angularly displaced with relation toone another, the angular displacement being such that the gas releasedat the cathode opposite one portion of the anode will not interfere withthe deposition in the active zone or area of the adjacent 1 anodeportions. The anode part 22 may in whole or in part have thecharacteristics of a spiral or sinuous shape. The anode portions 25 etseq. are preferably made in separate portions or sections, asillustrated. Such separate construction facilitates the manufacture andassembling of the anode structure, particularly where this is to be doneon the inside of a hollow vessel where the ingress is restricted. Theshape and area of the anode part 22 and of its portions 25 et seq., maybe chosen to best suit the conditions of the current densities, gasdisengagement, facilities for removing the gas, and the size of openingsencountered in the particular job to be carried out.

The cathode strip on which the metal is deposited is broadenedprogressively until the required or entire surface is covered with theelectrodeposited metal. To this end, means are provided for effectingrelative movement of the anode and cathode. Preferably the anode part 22is mounted upon a rotatable shaft 40, the part 22 being convenien'tlyattached to said shaft 40 by a plurality of arms at. These arms at aredetachably connected to the shaft 40 by means of separable hub portionsat (Fig. 3), so thatthe arms and anode part 22, where such latter partis in plurality of sections 25 et seq., may be passed separately throughthe opening, as the opening 12 in the vessel 10.

The shaft i0 is rotated in suitable manner, as by means of a worm andgear drive 48.

The shaft 40 may, as here shown, he made hollow (see Figs. 2 and 3) andelectrical conductors leading through said hollow shaft to theseveral'anode portions 25 et seq. The several conductors 50 may beconnected to a ring 52, in contact with the plus side of a generatorthrough the brushes 54.

Means for maintaining the temperature ofprovided. Conveniently,thesecomprise pipe connections 60,61, by means of which a circulation ofthe electrolyte into 'andout of the vessel may be provided, the incomingsolution having a temperature which will give to the solution in theVessel the desired approximately constant temperature.

The vessel itself is used as the container for the solution, and isusually filled to its top. The gas is vented through the upper opening12 in the tank, and auxiliary'means for facilitating the venting may beemployed if desired,

The vessel or other hollow article 10 is connected to the negative sideof the generator in any suitable manner, as by means of conductingstraps 7 O, 71.

One or more anode parts 22 may be provided. As here shown, the anodepart 22 and its portions 25 et seq. havediametrically oppositecorresponding sections. The description of one of these anode parts 22suffices for an understanding of the other or others.

The gas, as it rises, tends to distribute in the body of theelectrolyte, sothat at a suitable height above or distance away from anyparticularv angular portion, for example the angular portion 36, anotherportion, as the portion 75, occupying a similar angular position, may beused without substantial detriment.

For plating the end or ends of the vessel 10, suitable anode sections 80may be provided. These face theend of the vessel, and the end surfacedeflects the gas rising in the vessel from the cothode surfaceimmediately opposite the anode 80. These anode portions 80 arepreferably also arranged so as to defiect the gas toward the outlet 12.Suitable deflectors similar to anode sections 80 but ments. and becarried out in other modes of procedure than those specifically hereinillustrated and described.

What is claimed is:

1. An apparatus for electrodepositing metals suclfas chromium on theinside of hollow cathode articles, comprising an elongated anode havingangularly displaced portions, whereby the gaseous products released atthe cathode opposite one portion of the anode will not interferewith thedepbsition in the active zone or area of the adjacent anode portions. 7l

2. An apparatus for electrodepositing metals such as chromium on theinside of hollow cathode articles,comprising an elongated anode havingangularly displaced portions, whereby the gaseous products released h lltill

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at the cathode opposite one portion of the anode will not interfere withthe deposition in the active zone or area of the adjacent anodeportions, and means for moving said anode relative to said cathodesurface, whereby the surface of said cathode may be progressivelycoated.

3. An apparatus for electrodepositing metals such as chromium on theinside of hollow cathode articles,'comprising an elongated anode havingangularly displaced portions, whereby the gaseous products released atthe cathode opposite one portion ofthe anode will not interfere with thedeposition in the active zone or area of the adjacent anode portions andmeans for moving said anode relative to said cathode surface, where bythe surface of said cathode may be progressively coated, said meanscomprising a shaft-on which said anode is mounted.

a. An apparatus for electrodepositing metals such as chromium on theinside of hollow cathode articles, comprising an elongated anode havingangularly displaced portions, whereby the gaseous products released atthe cathode opposite one portion of the anode will not interfere withthe deposition in the active zone or area of the adjacent anodeportions, and means for moving said anode relative'to said cathodesurface, whereby the surface of-said cathode may be progressivelycoated, .said means comprising a shaft on which said anode is mounted,said anode being made of separate parts or sections, whereby they may bepassed through a restricted opening to the interior of the hollowcathode article, and built up .in situ therein. e j

5. An apparatus for electrodepositing metals such as chromium on theinside of hollow cathode articles, comprising an elongated anode havingangularly displaced portions, whereby the gaseous products released atthe cathode opposite one portion of the anode will not interfere withthe deposition in the "active zone or area of the adjacent anodeportions, and means for moving said lid anode relative to said cathodesurface, whereby the surface of said cathode may be progressivelycoated, said means comprising a shaft on which said anode is mounted,and means for rotating said shaft.

6. An apparatus for electrodepositing metals such as chromium'on theinside of hollow cathode articles, comprising an elongated anode havingangularly displaced portions, whereby the gaseous products released atthe cathode opposite one portion of the anode will not interfere, withthe deposition in the active zone or area of the adjacent anodeportions, said sections being separated from one another." I

7. An apparatus for electrodepositing metals such as cromium ontheinside of hollow cathode articles, comprising an elongated anodehaving angularly displaced portions, whereby the gaseous productsreleased at the cathode opposite one portion of the anode will-notinterfere with the deposition in the active zone or area of the adjacentanode portions, and means for venting said gaseous products.

8. The method of electrodepositin metals such as chromium on the inside0 hollow cathode articles, comprising directing the depositing currentonto the cathode along an elongated strip, portions of which areangularly displaced with relation to one another, and continuing thedeposition as a broadening band by progressively directing said currentto the cathode surface in like relation.

9. The method of electrodepositin metals such as chromium on the insideof hollow cathode articles, comprising directing the depositing currentonto the cathode along an elongated vertical stri portions of which areangularly displace with relation of one another, and continuing thedeposition as a broadening band by progressively directing said currentto the cathode surface in like relation.

10. In a method of electrodepositing metals such as chromium on theinside of hollow cathode articles, comprising directing the depositingcurrent onto the cathode article along a vertical strip, portions ofwhich are angularl displaced with relation to one another, w iereby thegaseous products released at one portion of the cathode strip receivingdeposited metal will not interfere with the deposition on the adjacentportions of said strip.

11. In a method of electrodepositing metals cathode articles, comprisingdirecting the depositing current onto the cathode articlealong avertical strip, portions of which are angularly displaced with relationto one another, whereby the gaseous products released at one portion ofthecathode stri receiving deposited metal will not inter ere with thedeposition on the adjacent portions of said strilpl, towardt e centerportion of said hollow 'article, and venting said deflected gases.

13. In a method of electro-depositin 'met-,

als' such as chromium on the inside of long hollow articles comprising.standing said ardeflecting said gaseous products 4 meets;

ticles upright with plating solution therein, tion of the cathode stripreceiving deposited and directing the depositing current on to the metalwill not interfere with the deposition cathode article from an anode ina, progreson the upper portions of said strip. 1% ,sive band or stripoircumferentially of said In witness whereof, I have hereunto signed 5article, and of a height considerably less than my name, the height ofsaid cathode article, whereby the Y Y gaseous products released at thelower por- EWE W4 SCHWARTZ

